NEW YORK (Reuters Health) - In patients with chronic hepatitis C virus infection, rates of sustained virological response (SVR) are higher with peginterferon alpha-2a than with peginterferon alpha-2b, according to a Cochrane Hepato-Biliary Group systematic review and meta-analysis.

In an online report in Hepatology, the researchers acknowledge that "current evidence suggests that peginterferon alpha-2a is significantly superior to peginterferon alpha-2b" -- but they don't recommend one drug over the other, because there was "insufficient evidence to detect any differences regarding harms," and "any potential benefit must outweigh the risk."

Dr. Awad and co-authors note that a large trial reported recently in The New England Journal of Medicine found that both agents had similar safety and efficacy, but "findings from a single randomized clinical trial, even a large one, are rarely definitive," they say.

Data from 11 trials indicated that discontinuation due to adverse events did not differ significantly based on peginterferon formulation.

However, the investigators add, "evidence on liver-related morbidity or mortality and adverse events is sparse, and the meta-analysis on adverse events is likely to be underpowered to detect any difference." Only one trial reported on all-cause mortality and none of the trials reported on liver-related morbidity.

The researchers conclude that additional trials are needed to shed light on how treatments that achieve SVR affect "clinically relevant outcomes such as risk of cirrhosis, hepatocellular carcinoma, and mortality."

They note in the article that peginterferon alpha-2a is marketed as Pegasys by Hoffmann-La Roche, and peginterferon alpha-2b is sold as Peg-Intron by Schering-Plough Corporation.